Most internet stores are run by people just like you. If they are selling the same products, they most likely have the same distributors and are required to follow the same distributor-set rules.
Knowing this, I again want to reinforce that it isn’t always priced that will allow you to win the battle over the long term, but quality and incentive.
One of the best ways to be a few steps ahead of your competitors at all times is to visit their sites often. Bookmark them and visit them every week to look for changes or ways you can outsmart them.
I will never advocate stealing information or graphics, through life experience honesty always gets you further, but if they have a section that looks like a good idea, and you think you could do it better, do it! If they are having a sale, have a similar sale with an extra incentive. This is business, not the Cub Scouts.
Another great way to keep track of your competitors is to sign up for their newsletter.
Also among your competition will be the multi-billion dollar retail stores. These are sometimes the most difficult, but also the easiest competitors.
Difficult because if they have low prices, you probably can’t beat them (but again, do you?). They can access lower prices because they have buying power. Those companies buy in such bulk that they get a deep discount and can afford to sell cheap.
But they are easy competitors in that they are not very reactive. With your online stores, you’ll probably be doing something on it every day, these companies don’t! In fact, they will only compete with you on the most basic levels. Don’t worry about them too much, your biggest competitors are the people just like yourself!